Systems and methods for evaluating treatment tables for refractive surgery

ABSTRACT

Treatment table verification techniques involve comparing intended refraction information with expected optical refraction information, and validating or qualifying the treatment table based on such comparisons. Systems and methods for verifying treatment tables provide enhanced safety for laser vision correction treatments.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/749,751 filed Mar. 30, 2010, which is related to U.S. patentapplication Ser. No. 10/825,864 filed Dec. 20, 2004, the entire contentof which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

Embodiments of the present invention relate generally to the field ofoptical correction, and in particular encompass methods, devices, andsystems for evaluating treatment tables for use in treating patientspresenting vision conditions.

In a typical refractive surgical procedure, aberrations of the patient'seye are examined with wavefront analysis or other measurementprocedures. In turn, the measurement information can be used to generatea treatment table for the patient. Laser eye surgery systems and othervision treatment techniques often involve the use of such treatmenttables.

A laser treatment table can include, for example, a listing ofcoordinate references for delivery of a laser beam during an ablation ofthe cornea. In some cases, a treatment table includes the value of thediscrete radial and angular positions of the optomechanical elementsused to scan an image over a portion of the anterior corneal surface.Treatment tables may also contain laser pulse instructions such as size,location, sequence, and the number of laser pulses per position. Inorder to provide a patient with an effective, predictable, and safesurgical procedure, it is important to generate and implement atreatment table which is accurate.

Although current and proposed treatment devices and methods may providereal benefits to patients in need thereof, still further advances wouldbe desirable. For example, there continues to be a need for improvedablation systems and methods that accurately assess, verify, andvalidate treatment tables. Embodiments of the present invention providesolutions that address certain limitations which may be associated withknown techniques, and hence provide answers to at least some of theseoutstanding needs.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention encompass systems and methods forvalidating or qualifying treatment tables for use in refractive surgeryprocedures. These techniques ensure that treatment tables are generatedas intended for a particular patient, and are not created unexpectedly.Exemplary validation techniques involve the use of a standalone,independent procedure which includes comparing an intended refractionwith an expected optical refraction based on a treatment table that isintended for use with the patient. In some cases, the treatment table isqualified or approved to be released for use only if the differencebetween the intended refraction and the expected refraction is within apre-defined tolerance. Hence, embodiments of the present inventionprovide improvements in ablation control, laser, ablation profilegeneration, treatment generation, and process or software verificationand validation. Relatedly, techniques for evaluating a treatment tableas described herein can be used to increase the safety of anophthalmologic refractive surgery.

In an exemplary approach, laser pulse instructions, which may includesize, location, and sequence information, can be used to derive anexpected optical refraction, which is then compared with an intendedrefraction for the patient. Some evaluation or verification methods mayinclude inputting a treatment table containing laser ablationinstructions, and calculating an expected optical refraction based onthe laser instructions, where the expected refraction includes sphere,cylinder, and axis components. Methods may also include inputting anintended optical refraction for a patient, where the intended refractionincludes sphere, cylinder, and axis components, and evaluating orverifying the treatment table by comparing the expected and intendedrefractions. If the expected refraction is sufficiently similar to theintended refraction, the treatment table may be approved for use. If theexpected refraction deviates significantly from the intended refraction,however, the treatment table can be disqualified. Hence, embodiments ofthe present invention provide a beneficial safety feature for refractivesurgery procedures.

In a first aspect, embodiments of the present invention encompassmethods of evaluating a treatment table for use in an ophthalmologicrefractive surgery for a patient. Methods may include, for example,inputting a treatment table containing laser ablation instructions fortreating the patient into a treatment instructions module, determining asimulated ablation for the patient based on the laser ablationinstructions with a simulation ablation module, inputting a pupildimension of the patient into a pupil dimension module, and determiningan expected optical refraction for the patient based on the pupildimension and the simulated ablation with an expected optical refractionmodule, where the expected optical refraction for the patient isdependent on a sphere ophthalmic term characterized by a set of secondradial order polynomial terms, a cylinder ophthalmic term characterizedby the set of second radial order polynomial terms, and an axisophthalmic term characterized by the set of second radial orderpolynomial terms, and where the expected optical refraction profile isindependent of a piston ophthalmic term characterized by a zero radialorder polynomial term, an x-tilt ophthalmic term characterized by a setof first radial order polynomial terms, and a y-tilt ophthalmic termcharacterized by the set of first radial order polynomial terms. Methodsmay further include inputting an intended optical refraction for thepatient into an intended refraction module, where the intended opticalrefraction for the patient is dependent on a sphere ophthalmic term, acylinder ophthalmic term, and an axis ophthalmic term, and where theintended optical refraction profile is independent of a pistonophthalmic term, an x-tilt ophthalmic term, and a y-tilt ophthalmicterm. Additionally, methods may include evaluating the treatment tableby comparing the expected and intended optical refractions for thepatient with a comparison module. In some cases, the set of secondradial order polynomial terms includes a set of second radial orderZernike polynomial terms, the zero radial order polynomial term includesa zero radial order Zernike polynomial term, and the set of first radialorder polynomial terms includes a set of first radial order Zernikepolynomial terms. In some cases, the set of second radial orderpolynomial terms includes a set of second radial order Seidel powerseries terms, the zero radial order polynomial term includes a zeroradial order Seidel power series term, and the set of first radial orderpolynomial terms includes a set of first radial order Seidel powerseries terms. Optionally, the expected optical refraction and theintended optical refraction each correspond to a common plane. In someinstances, the expected optical refraction and the intended opticalrefraction each correspond to a corneal plane. In some instances, thepupil dimension of the patient corresponds to a wavefront diameterrelated to a wavescan of the patient. In some instances, the pupildimensional of the patient comprises a pupil diameter that is equivalentto the wavefront diameter. According to some embodiments, the pupildimension of the patient is a pupil diameter of about 4 mm. Methods mayalso include determining if a difference between the expected andintended optical refractions for the patient is within a pre-definedtolerance. Methods may also include qualifying the treatment table foruse in the ophthalmologic refractive surgery for the patient if thedifference between the expected and intended optical refractions iswithin the pre-defined tolerance. Some method may include disqualifyingthe treatment table for use in the ophthalmologic refractive surgery forthe patient if the difference between the expected and intended opticalrefractions is not within the pre-defined tolerance.

In another aspect, embodiments of the present invention encompasssystems for evaluating a treatment table for use in an ophthalmologicrefractive surgery for a patient. Exemplary systems may include atreatment instructions module that accepts a treatment table containinglaser ablation instructions for treating the patient, a simulationablation module having a tangible medium embodying machine-readable codethat determines a simulated ablation for the patient based on the laserablation instructions, a pupil dimension module that accepts a pupildimension of the patient, and an expected optical refraction modulehaving a tangible medium embodying machine-readable code that determinesan expected optical refraction for the patient based on the pupildimension and the simulated ablation, where the expected opticalrefraction for the patient is dependent on a sphere ophthalmic termcharacterized by a set of second radial order polynomial terms, acylinder ophthalmic term characterized by the set of second radial orderpolynomial terms, and an axis ophthalmic term characterized by the setof second radial order polynomial terms, and where the expected opticalrefraction profile is independent of a piston ophthalmic termcharacterized by a zero radial order polynomial term, an x-tiltophthalmic term characterized by a set of first radial order polynomialterms, and a y-tilt ophthalmic term characterized by the set of firstradial order polynomial terms. Systems may further include an intendedrefraction module that accepts an intended optical refraction for thepatient, where the intended optical refraction for the patient isdependent on a sphere ophthalmic term, a cylinder ophthalmic term, andan axis ophthalmic term, and where the intended optical refractionprofile is independent of a piston ophthalmic term, an x-tilt ophthalmicterm, and a y-tilt ophthalmic term. Additionally, systems may include acomparison module having a tangible medium embodying machine-readablecode that evaluates the treatment table by comparing the expected andintended optical refractions for the patient. In some systemembodiments, the set of second radial order polynomial terms includes aset of second radial order Zernike polynomial terms, the zero radialorder polynomial term includes a zero radial order Zernike polynomialterm, and the set of first radial order polynomial terms includes a setof first radial order Zernike polynomial terms. In some systems, theexpected optical refraction and the intended optical refraction eachcorrespond to a common plane. In some systems, the expected opticalrefraction and the intended optical refraction each correspond to acorneal plane. Exemplary systems may also include a validation modulehaving a tangible medium embodying machine-readable code that determinesif a difference between the expected and intended optical refractionsfor the patient is within a pre-defined tolerance, and a qualificationmodule having a tangible medium embodying machine-readable code thatqualifies the treatment table for use in the ophthalmologic refractivesurgery for the patient if the difference between the expected andintended optical refractions is within the pre-defined tolerance.

In another aspect, embodiments of the present invention encompass acomputer program product embodied on a tangible computer readable mediumthat includes computer code for inputting a treatment table containinglaser ablation instructions for treating the patient, computer code fordetermining a simulated ablation for the patient based on the laserablation instructions, computer code for inputting a pupil dimension ofthe patient, and computer code for determining an expected opticalrefraction for the patient based on the pupil dimension and thesimulated ablation, where the expected optical refraction for thepatient is dependent on a sphere ophthalmic term characterized by a setof second radial order polynomial terms, a cylinder ophthalmic termcharacterized by the set of second radial order polynomial terms, and anaxis ophthalmic term characterized by the set of second radial orderpolynomial terms, and where the expected optical refraction profile isindependent of a piston ophthalmic term characterized by a zero radialorder polynomial term, an x-tilt ophthalmic term characterized by a setof first radial order polynomial terms, and a y-tilt ophthalmic termcharacterized by the set of first radial order polynomial terms.Computer program products may also include computer code for inputtingan intended optical refraction for the patient, where the intendedoptical refraction for the patient is dependent on a sphere ophthalmicterm, a cylinder ophthalmic term, and an axis ophthalmic term, and wherethe intended optical refraction profile is independent of a pistonophthalmic term, an x-tilt ophthalmic term, and a y-tilt ophthalmicterm, and computer code for evaluating the treatment table by comparingthe expected and intended optical refractions for the patient with acomparison module. For some computer program products, the set of secondradial order polynomial terms includes a set of second radial orderZernike polynomial terms, the zero radial order polynomial term includesa zero radial order Zernike polynomial term, and the set of first radialorder polynomial terms includes a set of first radial order Zernikepolynomial terms. For some computer program products, the expectedoptical refraction and the intended optical refraction each correspondto a common plane. For some computer program products, the expectedoptical refraction and the intended optical refraction each correspondto a corneal plane. Exemplary computer program products may also includecomputer code for determining if a difference between the expected andintended optical refractions for the patient is within a pre-definedtolerance, and computer code for qualifying the treatment table for usein the ophthalmologic refractive surgery for the patient if thedifference between the expected and intended optical refractions iswithin the pre-defined tolerance.

For a fuller understanding of the nature and advantages of the presentinvention, reference should be had to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a laser ablation system according to an embodiment ofthe present invention.

FIG. 2 illustrates a simplified computer system according to anembodiment of the present invention.

FIG. 3 illustrates a wavefront measurement system according to anembodiment of the present invention.

FIG. 3A illustrates another wavefront measurement system according to anembodiment of the present invention.

FIG. 4 shows aspects of an evaluation system according to embodiments ofthe present invention.

FIG. 4A depicts aspects of an evaluation method according to embodimentsof the present invention.

FIG. 5 shows aspects of an evaluation system according to embodiments ofthe present invention.

FIG. 6 illustrates aspects of residual error according to embodiments ofthe present invention.

FIG. 7 illustrates aspects of residual sphere and cylinder according toembodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention include systems and methods whichuse treatment table content (e.g. laser pulse instructions) to derive orgenerate an expected optical refraction, and compare that expectedrefraction with an intended refraction for the patient Typically,optical refractions include sphere, cylinder, and axis components. Inaddition to the treatment table laser instructions, the derived expectedrefraction may also take into account the treatment or vertex plane, forexample to ensure that the derived refraction plane matches the intendedrefraction plane. Further, embodiments of the present invention providesystems and methods for treatment table validation that implement aseparate, independent set of code to ensure that a planned refraction inthe treatment table is consistent with the desired refraction. Thus, anexemplary method may involve inputting an intended refraction for apatient, inputting a treatment table containing laser ablationinstructions, calculating an expected optical refraction based on thetreatment table and optionally a vertex or treatment plane parameter,comparing the expected optical refraction with the intended refraction,and evaluating the treatment table based on the comparison of theexpected optical refraction with the input refraction. If the expectedoptical refraction deviates significantly from the intended refraction,the treatment table will be disqualified.

In some cases, an intended optical refraction is dependent uponophthalmic sphere, cylinder, and axis terms that are not based onZernike values, whereas an expected optical refraction is dependent onsphere, cylinder, and axis terms that are based on Zernike values.Intended optical refractions, such as those dependent on ophthalmicsphere, cylinder, and axis terms, can be related to Zernikes (e.g.wavefront-guided), or physician input (e.g. VSS Refractive™ technique,non-wavefront guided, or manifest refraction). Optionally,wavefront-guided or nonwavefront-guided data can be used on conjunctionwith a physician adjustment.

Embodiments of the present invention can be readily adapted for use withexisting laser systems, wavefront measurement systems, and other opticalmeasurement devices. Although the systems, software, and methods of thepresent invention are described primarily in the context of a laser eyesurgery system, it should be understood the present invention may beadapted for use in alternative eye treatment procedures, systems, ormodalities, such as spectacle lenses, intraocular lenses, accommodatingIOLs, contact lenses, corneal ring implants, collagenous corneal tissuethermal remodeling, corneal inlays, corneal onlays, other cornealimplants or grafts, and the like. Relatedly, systems, software, andmethods according to embodiments of the present invention are wellsuited for customizing any of these treatment modalities to a specificpatient. Thus, for example, embodiments encompass custom intraocularlenses, custom contact lenses, custom corneal implants, and the like,which can be configured to treat or ameliorate any of a variety ofvision conditions in a particular patient based on their unique ocularcharacteristics or anatomy. Aspects of techniques described herein canbe implemented in a variety of laser and aberrometer devices, includingwithout limitation the VISX WaveScan WaveFront® System and VISX STAR 54®Excimer Laser System, the Wavelight® Alegretto and Tscherning-basedaberrometer; the Alcon Ladarvision® lasers and Ladarwave® aberrometer;the Bausch and Lomb Zyoptix® laser and related aberrometer, and theZeiss® laser and WASCA® aberrometer.

Turning now to the drawings, FIG. 1 illustrates a laser eye surgerysystem 10 of the present invention, including a laser 12 that produces alaser beam 14. Laser 12 is optically coupled to laser delivery optics16, which directs laser beam 14 to an eye E of patient P. A deliveryoptics support structure (not shown here for clarity) extends from aframe 18 supporting laser 12. A microscope 20 is mounted on the deliveryoptics support structure, the microscope often being used to image acornea of eye E.

Laser 12 generally comprises an excimer laser, ideally comprising anargon-fluorine laser producing pulses of laser light having a wavelengthof approximately 193 nm. Laser 12 will preferably be designed to providea feedback stabilized fluence at the patient's eye, delivered viadelivery optics 16. The present invention may also be useful withalternative sources of ultraviolet or infrared radiation, particularlythose adapted to controllably ablate the corneal tissue without causingsignificant damage to adjacent and/or underlying tissues of the eye.Such sources include, but are not limited to, solid state lasers andother devices which can generate energy in the ultraviolet wavelengthbetween about 185 and 205 nm and/or those which utilizefrequency-multiplying techniques. Hence, although an excimer laser isthe illustrative source of an ablating beam, other lasers may be used inthe present invention.

Laser system 10 will generally include a computer or programmableprocessor 22. Processor 22 may comprise (or interface with) aconventional PC system including the standard user interface devicessuch as a keyboard, a display monitor, and the like. Processor 22 willtypically include an input device such as a magnetic or optical diskdrive, an internet connection, or the like. Such input devices willoften be used to download a computer executable code from a tangiblestorage media 29 embodying any of the methods of the present invention.Tangible storage media 29 may take the form of a floppy disk, an opticaldisk, a data tape, a volatile or non-volatile memory, RAM, or the like,and the processor 22 will include the memory boards and other standardcomponents of modern computer systems for storing and executing thiscode. Tangible storage media 29 may optionally embody wavefront sensordata, wavefront gradients, a wavefront elevation map, a treatment map, acorneal elevation map, and/or an ablation table. While tangible storagemedia 29 will often be used directly in cooperation with an input deviceof processor 22, the storage media may also be remotely operativelycoupled with processor by means of network connections such as theinternet, and by wireless methods such as infrared, Bluetooth, or thelike.

Laser 12 and delivery optics 16 will generally direct laser beam 14 tothe eye of patient P under the direction of a computer 22. Computer 22will often selectively adjust laser beam 14 to expose portions of thecornea to the pulses of laser energy so as to effect a predeterminedsculpting of the cornea and alter the refractive characteristics of theeye. In many embodiments, both laser beam 14 and the laser deliveryoptical system 16 will be under computer control of processor 22 toeffect the desired laser sculpting process, with the processor effecting(and optionally modifying) the pattern of laser pulses. The pattern ofpulses may by summarized in machine readable data of tangible storagemedia 29 in the form of a treatment table, and the treatment table maybe adjusted according to feedback input into processor 22 from anautomated image analysis system in response to feedback data providedfrom an ablation monitoring system feedback system. Optionally, thefeedback may be manually entered into the processor by a systemoperator. Such feedback might be provided by integrating the wavefrontmeasurement system described below with the laser treatment system 10,and processor 22 may continue and/or terminate a sculpting treatment inresponse to the feedback, and may optionally also modify the plannedsculpting based at least in part on the feedback. Measurement systemsare further described in U.S. Pat. No. 6,315,413, the full disclosure ofwhich is incorporated herein by reference.

Laser beam 14 may be adjusted to produce the desired sculpting using avariety of alternative mechanisms. The laser beam 14 may be selectivelylimited using one or more variable apertures. An exemplary variableaperture system having a variable iris and a variable width slit isdescribed in U.S. Pat. No. 5,713,892, the full disclosure of which isincorporated herein by reference. The laser beam may also be tailored byvarying the size and offset of the laser spot from an axis of the eye,as described in U.S. Pat. Nos. 5,683,379, 6,203,539, and 6,331,177, thefull disclosures of which are incorporated herein by reference.

Still further alternatives are possible, including scanning of the laserbeam over the surface of the eye and controlling the number of pulsesand/or dwell time at each location, as described, for example, by U.S.Pat. No. 4,665,913, the full disclosure of which is incorporated hereinby reference; using masks in the optical path of laser beam 14 whichablate to vary the profile of the beam incident on the cornea, asdescribed in U.S. Pat. No. 5,807,379, the full disclosure of which isincorporated herein by reference; hybrid profile-scanning systems inwhich a variable size beam (typically controlled by a variable widthslit and/or variable diameter iris diaphragm) is scanned across thecornea; or the like. The computer programs and control methodology forthese laser pattern tailoring techniques are well described in thepatent literature.

Additional components and subsystems may be included with laser system10, as should be understood by those of skill in the art. For example,spatial and/or temporal integrators may be included to control thedistribution of energy within the laser beam, as described in U.S. Pat.No. 5,646,791, the full disclosure of which is incorporated herein byreference. Ablation effluent evacuators/filters, aspirators, and otherancillary components of the laser surgery system are known in the art.Further details of suitable systems for performing a laser ablationprocedure can be found in commonly assigned U.S. Pat. Nos. 4,665,913,4,669,466, 4,732,148, 4,770,172, 4,773,414, 5,207,668, 5,108,388,5,219,343, 5,646,791 and 5,163,934, the complete disclosures of whichare incorporated herein by reference. Suitable systems also includecommercially available refractive laser systems such as thosemanufactured and/or sold by Alcon, Bausch & Lomb, Nidek, WaveLight,LaserSight, Schwind, Zeiss-Meditec, and the like. Basis data can befurther characterized for particular lasers or operating conditions, bytaking into account localized environmental variables such astemperature, humidity, airflow, and aspiration.

FIG. 2 is a simplified block diagram of an exemplary computer system 22that may be used by the laser surgical system 10 of the presentinvention. Computer system 22 typically includes at least one processor52 which may communicate with a number of peripheral devices via a bussubsystem 54. These peripheral devices may include a storage subsystem56, comprising a memory subsystem 58 and a file storage subsystem 60,user interface input devices 62, user interface output devices 64, and anetwork interface subsystem 66. Network interface subsystem 66 providesan interface to outside networks 68 and/or other devices, such as thewavefront measurement system 30.

User interface input devices 62 may include a keyboard, pointing devicessuch as a mouse, trackball, touch pad, or graphics tablet, a scanner,foot pedals, a joystick, a touchscreen incorporated into the display,audio input devices such as voice recognition systems, microphones, andother types of input devices. User input devices 62 will often be usedto download a computer executable code from a tangible storage media 29embodying any of the methods of the present invention. In general, useof the term “input device” is intended to include a variety ofconventional and proprietary devices and ways to input information intocomputer system 22.

User interface output devices 64 may include a display subsystem, aprinter, a fax machine, or non-visual displays such as audio outputdevices. The display subsystem may be a cathode ray tube (CRT), aflat-panel device such as a liquid crystal display (LCD), a projectiondevice, or the like. The display subsystem may also provide a non-visualdisplay such as via audio output devices. In general, use of the term“output device” is intended to include a variety of conventional andproprietary devices and ways to output information from computer system22 to a user.

Storage subsystem 56 can store the basic programming and data constructsthat provide the functionality of the various embodiments of the presentinvention. For example, a database and modules implementing thefunctionality of the methods of the present invention, as describedherein, may be stored in storage subsystem 56. These software modulesare generally executed by processor 52. In a distributed environment,the software modules may be stored on a plurality of computer systemsand executed by processors of the plurality of computer systems. Storagesubsystem 56 typically comprises memory subsystem 58 and file storagesubsystem 60.

Memory subsystem 58 typically includes a number of memories including amain random access memory (RAM) 70 for storage of instructions and dataduring program execution and a read only memory (ROM) 72 in which fixedinstructions are stored. File storage subsystem 60 provides persistent(non-volatile) storage for program and data files, and may includetangible storage media 29 (FIG. 1) which may optionally embody wavefrontsensor data, wavefront gradients, a wavefront elevation map, a treatmentmap, and/or an ablation table. File storage subsystem 60 may include ahard disk drive, a floppy disk drive along with associated removablemedia, a Compact Digital Read Only Memory (CD-ROM) drive, an opticaldrive, DVD, CD-R, CD-RW, solid-state removable memory, and/or otherremovable media cartridges or disks. One or more of the drives may belocated at remote locations on other connected computers at other sitescoupled to computer system 22. The modules implementing thefunctionality of the present invention may be stored by file storagesubsystem 60.

Bus subsystem 54 provides a mechanism for letting the various componentsand subsystems of computer system 22 communicate with each other asintended. The various subsystems and components of computer system 22need not be at the same physical location but may be distributed atvarious locations within a distributed network. Although bus subsystem54 is shown schematically as a single bus, alternate embodiments of thebus subsystem may utilize multiple busses.

Computer system 22 itself can be of varying types including a personalcomputer, a portable computer, a workstation, a computer terminal, anetwork computer, a control system in a wavefront measurement system orlaser surgical system, a mainframe, or any other data processing system.Due to the ever-changing nature of computers and networks, thedescription of computer system 22 depicted in FIG. 2 is intended only asa specific example for purposes of illustrating one embodiment of thepresent invention. Many other configurations of computer system 22 arepossible having more or less components than the computer systemdepicted in FIG. 2.

Referring now to FIG. 3, one embodiment of a wavefront measurementsystem 30 is schematically illustrated in simplified form. In verygeneral terms, wavefront measurement system 30 is configured to senselocal slopes of a gradient map exiting the patient's eye. Devices basedon the Hartmann-Shack principle generally include a lenslet array tosample the gradient map uniformly over an aperture, which is typicallythe exit pupil of the eye. Thereafter, the local slopes of the gradientmap are analyzed so as to reconstruct the wavefront surface or map.

More specifically, one wavefront measurement system 30 includes an imagesource 32, such as a laser, which projects a source image throughoptical tissues 34 of eye E so as to form an image 44 upon a surface ofretina R. The image from retina R is transmitted by the optical systemof the eye (e.g., optical tissues 34) and imaged onto a wavefront sensor36 by system optics 37. The wavefront sensor 36 communicates signals toa computer system 22′ for measurement of the optical errors in theoptical tissues 34 and/or determination of an optical tissue ablationtreatment program. Computer 22′ may include the same or similar hardwareas the computer system 22 illustrated in FIGS. 1 and 2. Computer system22′ may be in communication with computer system 22 that directs thelaser surgery system 10, or some or all of the components of computersystem 22, 22′ of the wavefront measurement system 30 and laser surgerysystem 10 may be combined or separate. If desired, data from wavefrontsensor 36 may be transmitted to a laser computer system 22 via tangiblemedia 29, via an I/O port, via an networking connection 66 such as anintranet or the Internet, or the like.

Wavefront sensor 36 generally comprises a lenslet array 38 and an imagesensor 40. As the image from retina R is transmitted through opticaltissues 34 and imaged onto a surface of image sensor 40 and an image ofthe eye pupil P is similarly imaged onto a surface of lenslet array 38,the lenslet array separates the transmitted image into an array ofbeamlets 42, and (in combination with other optical components of thesystem) images the separated beamlets on the surface of sensor 40.Sensor 40 typically comprises a charged couple device or “CCD,” andsenses the characteristics of these individual beamlets, which can beused to determine the characteristics of an associated region of opticaltissues 34. In particular, where image 44 comprises a point or smallspot of light, a location of the transmitted spot as imaged by a beamletcan directly indicate a local gradient of the associated region ofoptical tissue.

Eye E generally defines an anterior orientation ANT and a posteriororientation POS. Image source 32 generally projects an image in aposterior orientation through optical tissues 34 onto retina R asindicated in FIG. 3. Optical tissues 34 again transmit image 44 from theretina anteriorly toward wavefront sensor 36. Image 44 actually formedon retina R may be distorted by any imperfections in the eye's opticalsystem when the image source is originally transmitted by opticaltissues 34. Optionally, image source projection optics 46 may beconfigured or adapted to decrease any distortion of image 44.

In some embodiments, image source optics 46 may decrease lower orderoptical errors by compensating for spherical and/or cylindrical errorsof optical tissues 34. Higher order optical errors of the opticaltissues may also be compensated through the use of an adaptive opticelement, such as a deformable mirror (described below). Use of an imagesource 32 selected to define a point or small spot at image 44 uponretina R may facilitate the analysis of the data provided by wavefrontsensor 36. Distortion of image 44 may be limited by transmitting asource image through a central region 48 of optical tissues 34 which issmaller than a pupil 50, as the central portion of the pupil may be lessprone to optical errors than the peripheral portion. Regardless of theparticular image source structure, it will be generally be beneficial tohave a well-defined and accurately formed image 44 on retina R.

In one embodiment, the wavefront data may be stored in a computerreadable medium 29 or a memory of the wavefront sensor system 30 in twoseparate arrays containing the x and y wavefront gradient valuesobtained from image spot analysis of the Hartmann-Shack sensor images,plus the x and y pupil center offsets from the nominal center of theHartmann-Shack lenslet array, as measured by the pupil camera 51 (FIG.3) image. Such information contains all the available information on thewavefront error of the eye and is sufficient to reconstruct thewavefront or any portion of it. In such embodiments, there is no need toreprocess the Hartmann-Shack image more than once, and the data spacerequired to store the gradient array is not large. For example, toaccommodate an image of a pupil with an 8 mm diameter, an array of a20×20 size (i.e., 400 elements) is often sufficient. As can beappreciated, in other embodiments, the wavefront data may be stored in amemory of the wavefront sensor system in a single array or multiplearrays.

While the methods of the present invention will generally be describedwith reference to sensing of an image 44, a series of wavefront sensordata readings may be taken. For example, a time series of wavefront datareadings may help to provide a more accurate overall determination ofthe ocular tissue aberrations. As the ocular tissues can vary in shapeover a brief period of time, a plurality of temporally separatedwavefront sensor measurements can avoid relying on a single snapshot ofthe optical characteristics as the basis for a refractive correctingprocedure. Still further alternatives are also available, includingtaking wavefront sensor data of the eye with the eye in differingconfigurations, positions, and/or orientations. For example, a patientwill often help maintain alignment of the eye with wavefront measurementsystem 30 by focusing on a fixation target, as described in U.S. Pat.No. 6,004,313, the full disclosure of which is incorporated herein byreference. By varying a position of the fixation target as described inthat reference, optical characteristics of the eye may be determinedwhile the eye accommodates or adapts to image a field of view at avarying distance and/or angles.

The location of the optical axis of the eye may be verified by referenceto the data provided from a pupil camera 52. In the exemplaryembodiment, a pupil camera 52 images pupil 50 so as to determine aposition of the pupil for registration of the wavefront sensor datarelative to the optical tissues.

An alternative embodiment of a wavefront measurement system isillustrated in FIG. 3A. The major components of the system of FIG. 3Aare similar to those of FIG. 3. Additionally, FIG. 3A includes anadaptive optical element 53 in the form of a deformable mirror. Thesource image is reflected from deformable mirror 98 during transmissionto retina R, and the deformable mirror is also along the optical pathused to form the transmitted image between retina R and imaging sensor40. Deformable mirror 98 can be controllably deformed by computer system22 to limit distortion of the image formed on the retina or ofsubsequent images formed of the images formed on the retina, and mayenhance the accuracy of the resultant wavefront data. The structure anduse of the system of FIG. 3A are more fully described in U.S. Pat. No.6,095,651, the full disclosure of which is incorporated herein byreference.

The components of an embodiment of a wavefront measurement system formeasuring the eye and ablations may comprise elements of a WaveScan®system, available from VISX, INCORPORATED of Santa Clara, Calif. Oneembodiment includes a WaveScan system with a deformable mirror asdescribed above. An alternate embodiment of a wavefront measuring systemis described in U.S. Pat. No. 6,271,915, the full disclosure of which isincorporated herein by reference. It is appreciated that any wavefrontaberrometer could be employed for use with the present invention.Relatedly, embodiments of the present invention encompass theimplementation of any of a variety of optical instruments provided byWaveFront Sciences, Inc., including the COAS wavefront aberrometer, theClearWave contact lens aberrometer, the CrystalWave IOL aberrometer, andthe like.

FIG. 4 depicts aspects of an evaluation system 400 according toembodiments of the present invention. As shown here, system 400 mayinclude an Input Refraction module 412, a Wavefront module 422, aZernike Reconstruction module 424, a Wavefront Refraction module 426, aPhysician Adjustment module 432, a Nomogram Adjustment module 434, anIntended Refraction module 436, a Treatment Instructions module 442, aPupil Dimension module 443, a Simulated Ablation module 444, a ZernikeDecomposition module 446, an Expected Refraction module 448, and aComparison module 452.

Input Refraction

The Input Refraction module 412 can operate to receive, process, andtransmit information related to original refractions from the patient,such as VSS Refractive™ technology (Variable Spot Scanning) data, ormanifest or subjective refraction. This information can correspond tonon-wavefront guided data. According to some embodiments, InputRefraction module 412 can be configured to receive information regardingthe refractive error of a patient. Such refractive error information mayinclude sphere, cylinder, cylinder axis, and vertex distance data.Hence, low order aberration information can be used. For example,refractive error information may correspond to input cases such asmyopia or hyperopia. In some cases, the refractive error information maybe obtained at or correlated with a spectacle plane (e.g. 12.5 mmvertex). Input Refraction module 412 can also be configured to convertthe input refractive error information to refractive error informationrelative to the corneal plane. Such plane conversion techniques arediscussed in G.-m. Dai, Wavefront Optics for Vision Correction (SPIEPress, 2008), which is incorporated herein by reference. Planeconversion techniques can correspond to a vertex distance change oradjustment. Embodiments of the present invention encompass systems andmethods for converting between treatment planes, user-defined orphysician-defined planes, spectacle planes, corneal planes, pupilplanes, and other planes of interest. Further, Input Refraction module412 can be configured to output or transmit the corneal plane refractiveerror information, which may include sphere, cylinder, cylinder axis,and vertex distance components. In some cases, the refractive errorinformation can be presented in the following format: sphere valueDS/cylinder value DC×axis value @ vertex distance value. Optionally,Sphere and Cylinder can be represented in terms of diopters of power,Axis can be represented in terms of angle or degrees, and VertexDistance can be represented in terms of millimeters. Sphere typicallypresents a measurement of lens power for myopia (negative) or hyperopia(positive), and cylinder typically presents a measurement of lens powerfor astigmatism. Hence, this refraction information and other eyemeasurements can be processed, as described herein, and compared withprocessed treatment table information to qualify the treatment table.

Wavefront

The Wavefront module 422 can operate to receive, process, and transmitinformation related to CustomVue™ technology or wavefront guided data.According to some embodiments, Wavefront module 422 can be configured toreceive information regarding the wavefront error of a patient. Suchwavefront error information may include wavefront map and wavefrontdiameter data. In some cases, the wavefront error information may beobtained at or correlated with a pupil plane. Wavefront module 422 canalso be configured to process Hartmann-Shack spot diagram data, forexample as described in G.-m. Dai, Wavefront Optics for VisionCorrection (SPIE Press, 2008). Hartmann-Shack data can correspond towavefront map data and wavefront diameter data. Typically,Hartmann-Shack data provides x and y shift information corresponding toarray lenslets, and a wavefront data map can be derived from theHartmann-Shack data. The map may optionally be associated with aparticular wavefront diameter, particularly when the map is describedwith Zernike terms. In some cases, the map may be represented by adiscrete matrix. Hence, Wavefront module 422 can be configured to outputor transmit wavefront slope data, which may include x- and y-slopeinformation.

Zernike Reconstruction

The Zernike Reconstruction module 424 can operate to receive informationsuch as wavefront slope data, including for example x- and y-slope data.Zernike Reconstruction module 424 can also be configured to process thewavefront slope data with a Zernike reconstruction technique to obtainZernike coefficient data, for example as described in G.-m. Dai,Wavefront Optics for Vision Correction (SPIE Press, 2008). Further,Zernike Reconstruction module 424 can be configured to output ortransmit the Zernike coefficient information.

Wavefront Refraction

The Wavefront Refraction module 426 can operate to receive Zernikecoefficient information, such as data related to z3, z4, and z5 Zernikecoefficients. Wavefront Refraction module 426 can also be configured toreceive wavefront diameter information. What is more, WavefrontRefraction module 426 can be configured to determine or calculatewavefront refraction information, for example based on Zernikecoefficients and wavefront diameter, as discussed in G.-m. Dai,Wavefront Optics for Vision Correction (SPIE Press, 2008). The wavefrontrefraction information can be generated so as to correlated with a pupilplane, or with a corneal plane. Further, Wavefront Refraction module 426can transmit or output the wavefront refraction information.

Physician Adjustment

The Physician Adjustment module 432 can be configured to receiveinformation related to additional refractive correction at the uservertex or plane which may be selected or desired by a physician oroperator. The selected plane can correspond to the pupil plane, thecornea plane, the spectacle plane, or some other user-defined plane. ThePhysician Adjustment can be applied at the selected or user-definedplane. For example, if the user vertex or plane corresponds to aspectacle plane, the physician can apply the adjustment at the spectacleplane as well. Hence, if the physician desired to add another diopter oftreatment, the additional diopter could be applied at the spectacleplane when the physician is planning for a particular treatment. Theadjustment is combined with the correction, and the combination can beconverted to another plane, for example the corneal plane. PhysicianAdjustment module 432 can also be configured to convert the physicianadjustment to the corneal plane, as described in G.-m. Dai, WavefrontOptics for Vision Correction (SPIE Press, 2008). Moreover, PhysicianAdjustment module 432 can be configured to transmit or outputinformation relating the physician adjustment at the corneal plane. Suchinformation corresponding to the corneal plane, or another selectedplane, can be used for comparison and evaluation as discussed elsewhereherein.

Nomogram Adjustment

The Nomogram Adjustment module 434 can be configured to receiveinformation related to a percentage of a treatment target multiplicationfactor. Nomogram Adjustment module 434 can also be configured tomultiply the nomogram factor. The multiplication factor can bedetermined by the sum of one plus the nomogram adjustment percentage.For example, if the nomogram adjustment percentage is 8%, themultiplication factor can be calculated as one plus 8/100, or 1.08.According to some embodiments, the nomogram adjustment percentage can bea value within a range from about −10% to about +10%. Relatedly,according to some embodiments, the multiplication factor can be a valuewithin a range from about 0.9 to about 1.1. Further, the NomogramAdjustment module 434 can be configured to transmit or outputinformation corresponding to a multiplied treatment target.

Intended Refraction

The Intended Refraction module 436 can operate to receive informationdirectly from Wavefront Refraction module 426, or from PhysicianAdjustment module 432 or Nomogram Adjustment module 434. According tosome embodiments, Intended Refraction module 436 can be configured toreceive information that is similar to or the same as the inputrefraction discussed above in relation to the Input Refraction module412. For example, Intended Refraction module 436 can be configured toreceive information regarding the refractive error of a patient. Suchrefractive error information may include sphere, cylinder, cylinderaxis, and vertex distance data. In some cases, the refractive errorinformation may be obtained at or correlated with a spectacle plane.Typically, the refractive error information or intended refractioninformation is based on a correction that is planned for application tothe patient's eye. Such intended or desired refractive correctioninformation can also be represented in terms of ocular or opticalrefraction data. Intended Refraction module 436 can also be configuredto convert the input refractive error information to refractive errorinformation relative to the corneal plane. Such plane conversiontechniques are discussed in G.-m. Dai, Wavefront Optics for VisionCorrection (SPIE Press, 2008). Further, Intended Refraction module 436can be configured to output or transmit the corneal plane refractiveerror information, which may include sphere, cylinder, cylinder axis,and vertex distance components. For example, Intended Refraction module436 can be configured to transmit refractive information that isdependent upon or correlated with a sphere ophthalmic term, a cylinderophthalmic term, and an axis ophthalmic term.

In some cases, the intended optical refraction can be related to Zerniketerms, and in some cases the intended optical refraction can be relatedto manifest refraction which is used in VSS refractive. For example, theintended optical refraction can be dependent upon ophthalmic terms suchas sphere, cylinder, and axis that are not directly related to Zerniketerms. In some instances, the resolution of a wavefront aberrometerdevice may be greater than that of a phoropter device. Hence, a patientreceiving a wavefront aberrometer exam that provides a result of 3.75diopters, may also receive a phoropter exam that provides a result of3.50 diopters. Either of the wavefront or manifest refraction resultsmay be used.

Treatment Instructions

The Treatment Instructions module 442 can be configured to receiveinformation related to a treatment target. Further, TreatmentInstructions module 442 can operate to process the treatment targetinformation according to a simulated annealing least squares algorithm(SALSA) to obtain a treatment table or set of laser ablationinstructions for a patient, as described in G.-m. Dai, Wavefront Opticsfor Vision Correction (SPIE Press, 2008). The treatment table mayinclude laser instruction parameters such as iris size, x- andy-scanning positions or locations, shot-to-shot or beam pulse delaytime, pulse or beam size, and other ablation instruction parameters. Thelaser parameters can be used to deliver an ablation that corresponds tothe Zernike polynomial terms, or other basis function terms such asSeidel series terms. A refraction typically corresponds to a secondorder polynomial, and basis functions such as Zernike polynomials andSeidel series are well suited for characterizing refractions based oncalculation of second order coefficients. Treatment Instructions module442 may also be configured to transmit or output laser ablationinstructions, such as iris size, x- and y-scanning positions,shot-to-shot delay time, and the like. The treatment table maycharacterize information that has been processed via a table generationengine. When the ablation is simulated based on the ensemble of laserinstructions, the resulting volumetric information corresponds to theZernike terms.

Pupil Dimension

The Pupil Dimension module 443 can operate to process informationrelated to a pupil dimension of the patient. In some cases, PupilDimension module 443 can be configured to receive a selected wavefrontor pupil diameter, and to calculate a refraction corresponding to thepupil dimension. Such information can be transmitted to a ZernikeDecomposition module, as discussed elsewhere herein. In some cases, apupil diameter can correspond with a wavefront diameter used during awavefront exam, for example a wavefront exam which may be performed inconjunction with the operation of Wavefront module 422. The pupildimension may in some instances have a value within a range from about 3mm to about 7 mm. In some cases, the pupil dimension is a pupil diameterof about 4 mm. Hence, embodiments encompass techniques that calculate arefraction over a 4 mm pupil diameter, as well as other pupildimensions. Exemplary aspects of pupil dimension selection are discussedin U.S. Pat. No. 7,460,288, which is incorporated herein by reference.

Simulated Ablation

The Simulated Ablation module 444 can be configured to receiveinformation related to laser ablation instructions, such as iris size,x- and y-scanning positions or tracking distances, shot-to-shot delaytime, and the like. Simulated Ablation module 444 can also be configuredto process information related to a simulated laser ablation or laserablation instructions to obtain a simulated volume or tissue volumeplanned for removal, based on basis data. Often, specific basis datainformation is available for corresponding specific iris sizes. Hence,for each particular iris size there can be a corresponding basis datainformation. Further, Simulated Ablation module 444 can be configured tooutput or transmit the simulated volume or tissue volume intended to beremoved.

Zernike Decomposition

The Zernike Decomposition module 446 can be configured to receiveinformation related to a pupil dimension and a tissue volume beingremoved. Zernike Decomposition module 446 can also be configured toprocess the pupil dimension and tissue volume information according to asingular value decomposition method to obtain Zernike coefficient andwavefront diameter information. In some cases, Zernike Decompositionmodule 446 generates data related to a set of second radial orderZernike polynomial terms. The second order Zernike polynomials, z3 z4,and z5 are analytically related to sphere, cylinder, and axis. The groupof z3 z4, and z5 terms can be used to determine sphere. Similarly, thegroup of z3 z4, and z5 terms can be used to determine cylinder. Further,the group of z3 z4, and z5 terms can be used to determine axis. Aspectsof a singular value decomposition method are discussed in G.-m. Dai,Wavefront Optics for Vision Correction (SPIE Press, 2008). Further,Zernike Decomposition module 446 can be configured to transmit or outputinformation related to the Zernike coefficients and wavefront diameter.As discussed elsewhere herein, embodiments may encompass techniques thatinvolve other basis function coefficients or second order radialpolynomials, for example Seidel power series.

Expected Refraction

The Expected Refraction module 448 can be configured to receiveinformation regarding Zernike coefficients (e.g. z3, z4, and z5 terms)and a pupil dimension. Expected Refraction module 448 can be configuredto determine a wavefront refraction based on the Zernike coefficient andpupil dimension information. Aspects of a wavefront refractiondetermination are discussed in G.-m. Dai, Wavefront Optics for VisionCorrection (SPIE Press, 2008). Further, Expected Refraction module 448can be configured to transmit or output information related to anexpected optical refraction for the patient, which may include forexample a sphere ophthalmic term characterized by a set of second radialorder Zernike polynomial terms, a cylinder ophthalmic term characterizedby the set of second radial order Zernike polynomial terms, and an axisophthalmic term characterized by the set of second radial order Zernikepolynomial terms. Optical refraction information typically correspondsto second order wavefront data or low order aberrations, and isdistinctly different from a surface shape, height, or topography. Forexample, when piston is added, the surface shape changes, however thecurvature or refraction does not. Similarly, if a surface is tilted, thesurface changes, however the curvature or refraction does not. Pistoncorresponds to a zero order Zernike polynomial, and represents upward ordownward displacement of a wavefront. Relatedly, tilt corresponds to afirst order Zernike polynomial.

Comparison

The Comparison module 452 can operate to compare intended refractioninformation with expected optical refraction information. For example,intended spherical equivalent (which corresponds to sphere and cylinder)can be compared with expected spherical equivalent, intended cylindercan be compared with expected cylinder, and intended axis can becompared with expected axis. In some cases, Comparison module 452 can beconfigured to receive information regarding an intended refraction andan expected or achieved refraction, optionally adjusted to orcharacterized in terms of a common or user-defined plane such as thecorneal plane, pupil plane, or spectacle plane.

Because refractions are typically dependent upon the vertex plane, itmay be desirable to compare intended and expected optical refractioninformation that corresponds to a common or specific vertex plane.Exemplary vertex or refraction conversions which may be used aredescribed in U.S. Pat. No. 7,296,893, incorporated herein by reference.Hence, if the input refraction data corresponds to the spectacle plane,and the wavefront data corresponds to the pupil plane, embodiments ofthe present invention encompass techniques for converting this data sothat it may be compared with data corresponding to a common plane, suchas the corneal plane. Comparison module 452 can also be configured tocompare the intended refraction and expected optical refractioninformation. For example, Comparison module 452 can operate to determinean algebraic difference for the sphere, cylinder, and axis ophthalmicterms, and compare the differences with a tolerance for the ophthalmicterm. Comparison module 452 can also be configured to qualify ordisqualify a treatment table based on the comparison between therespective refraction differences and tolerances.

Typically, comparison module 452 operates to compare low orderaberration information related to the intended refraction with low orderaberration information related to the expected refraction. Embodimentsof the present invention also encompass techniques that involve thecomparison of high order aberration information related to the intendedrefraction with high order aberration information related to theexpected refraction.

High order aberrations encompass, for example, third order aberrationsincluding trefoil and coma, as well as fourth order aberrationsincluding Z(4, −4), Z(4, −2), spherical aberration, Z(4,2), and Z(4,4)errors. Generally, high order aberrations include third order errors andabove.

Hence, comparison techniques can involve comparing an expected opticalrefraction for the patient, which is based on a pupil dimension and asimulated ablation, with an intended optical refraction for the patient.The expected optical refraction can be dependent on a sphere ophthalmicterm characterized by a set of second radial order Zernike polynomialterms, a cylinder ophthalmic term characterized by the set of secondradial order Zernike polynomial terms, and an axis ophthalmic termcharacterized by the set of second radial order Zernike polynomialterms. The expected optical refraction profile can also be independentof a piston ophthalmic term characterized by a zero radial order Zernikepolynomial term, an x-tilt ophthalmic term characterized by a set offirst radial order Zernike polynomial terms, and a y-tilt ophthalmicterm characterized by the set of first radial order Zernike polynomialterms. The intended optical refraction for the patient can be dependenton a sphere ophthalmic term, a cylinder ophthalmic term, and an axisophthalmic term. Further, the intended optical refraction profile can beindependent of a piston ophthalmic term, an x-tilt ophthalmic term, anda y-tilt ophthalmic term.

Scaling

With continued reference to FIG. 4, evaluation techniques can beimplemented in various ways. For example, in a VSS refractive treatment,an evaluation technique may be implemented by using a scaling factor toscale down the refraction from the treatment table, without using ascaling factor to boost the treatment target. Such approaches are wellsuited for use with a Munnerlyn shape which is deeper than a parabolicshape. Relatedly, in a CustomVue® treatment, an evaluation technique maybe implemented by using a scaling factor, for example of 1.11, to boostthe treatment target, without using a scaling factor to scale down therefraction from the treatment table, for example without a parabolic orMunnerlyn scaling. With regard to the VSS technique, scaling can beapplied in a linear fashion, to a Munnerlyn or parabolic shape. In somecase, a Munnerlyn shape can be scaled so as to approach or approximate aparabolic shape. A parabolic shape represents a second order shape, anda Munnerlyn represents a second order shape as supplemented with higherorders. Hence, for the same refraction, a Munnerlyn shape and aparabolic shape can differ. A comparison can be performed either at thecorneal plane or at the vertex plane, or both. According to someembodiments, the treatment table should qualify or pass if thedifference between the refraction from the table and the initial inputrefraction is smaller than the criteria used for wavefront examselection during the treatment table creation phase. In some cases,embodiments of the present invention provide systems and methods forqualifying a VSS refractive treatment. Exemplary techniques canimplement a treatment qualification validation process whereby arefraction from a simulated tissue ablation is compared with an inputrefraction, for example to ensure that no abnormal tables have beencreated. Because the Munnerlyn shape and a parabolic shape may differ,it may be useful to convert a Munnerlyn refraction to a parabolicrefraction. Munnerlyn shapes are discussed generally at C. R. Munnerlyn,S. J. Koons, and J. Marshall, “Photorefractive keratectomy: A techniquefor laser refractive surgery,” J. Cataract Refract. Surg. 14, 46-52(1988), the entire content of which is incorporated herein by reference.Embodiments of the present invention encompass different types ofscaling. For example, the techniques disclosed herein may includerefraction scaling or shape scaling, both of which involvemultiplication. In some cases, it is possible to use scaling factors of1.015 for myopic sphere, 1.025 for hyperopic sphere, and 1.015 forcylinder to scale a refraction, for example as discussed in relation toEqs. (9) to (11) provided elsewhere herein. In some cases, it ispossible to use a scaling factor of 1.11 to scale a shape.

FIG. 4A illustrates an exemplary method 400 a of evaluating a treatmenttable for use in an ophthalmologic refractive surgery for a patient. Asshown here, such evaluation, verification, or qualification techniquesmay include inputting a treatment table containing laser ablationinstructions for treating the patient, as depicted by step 410 a.Methods may also include determining a simulated ablation for thepatient based on the laser ablation instructions as indicated by step420 a, and inputting a pupil dimension of the patient as indicated bystep 430 a. In an exemplary embodiment, an evaluation method may includedetermining an expected optical refraction for the patient based on thepupil dimension and the simulated ablations, as indicated by step 440 a,wherein the expected optical refraction for the patient is dependent ona sphere ophthalmic term characterized by a set of second radial orderZernike polynomial terms, a cylinder ophthalmic term characterized bythe set of second radial order Zernike polynomial terms, and an axisophthalmic term characterized by the set of second radial order Zernikepolynomial terms. Optionally, the expected optical refraction profilecan be independent of a piston ophthalmic term characterized by a zeroradial order Zernike polynomial term, an x-tilt ophthalmic termcharacterized by a set of first radial order Zernike polynomial terms,and a y-tilt ophthalmic term characterized by the set of first radialorder Zernike polynomial terms. Method embodiments may also includeinputting an intended optical refraction for the patient, as indicatedby step 450 a, wherein the intended optical refraction for the patientis dependent on a sphere ophthalmic term, a cylinder ophthalmic term,and an axis ophthalmic term, and wherein the intended optical refractionprofile is independent of a piston ophthalmic term, an x-tilt ophthalmicterm, and a y-tilt ophthalmic term. Further, methods may includecomparing the expected and intended optical refractions for the patient,as indicated by step 460 a. The refractions can be adjusted to orcorrelated with a common plane, such as the treatment plane, pupilplane, corneal plane, or spectacle plane, prior to the comparison. Insome cases, methods may include evaluating the treatment table based onthe comparison between the expected and intended optical refractions forthe patient, as indicated by step 470 a, and qualifying or disqualifyingthe treatment table based on the evaluation, as indicated by step 480 a.For example, evaluation methods may include determining a differencebetween the intended optical refraction and the expected opticalrefraction, and comparing that difference to a predefined tolerance. Ifthe difference between the intended optical refraction and the expectedoptical refraction is within the tolerance, the method may includequalifying or passing the treatment table, or otherwise approving thetreatment table for use. Such qualification techniques can provide anenhanced level of safety during a patient treatment, for example byhelping to ensure that a treatment table has not been altered or hacked.

Information corresponding to any of a variety of inputs may beprocessed, such as data related to a spectacle plane parameter, acorneal plane, a pupil plane, or any other desired vertex plane ordistance parameter.

FIG. 5 depicts aspects of an evaluation system 500 according toembodiments of the present invention. As shown here, system 500 mayinclude a Table Generation DLL module 510, a Treatment Validation DLLmodule 520, a Treatment Table module 530, an Independent TableValidation module 540, and a Final Table module 550.

As shown here, for a Table Generation DLL 510 or treatment generationengine, a validation process can be performed by a Treatment ValidationDLL 520 whereby a validation is conducted for various possiblesimulation annealing solutions. Moreover, a process to validate aready-to-use treatment corresponding to Treatment Table 530 can providea separate, independent step for validating a treatment table. Such anindependent validation technique can operate separately from a treatmenttable generation engine or a treatment table generation algorithm whichmay involve a simulated annealing process, and therefore does notincorporate possible error which may result, for example, due tounexpected error from third-party DLLs, from mal-operation of the usersthat is not captured in the fault tree analysis during the softwaredesign phase, or from other possible sources of error. For example, dueto possible unknown bugs or errors in the high level software code orembedded in third-party libraries (DLLs), or due to inappropriateoperation of the software, it is possible that a software that isverified and validated by Treatment Validation DLL 520 may still producean unwanted treatment table that can potentially result in a suboptimaltreatment. Hence, embodiments of the present invention encompassvalidation techniques for addressing situations where third partycomponents such as operating systems, computers, or DLL's introduceerror or are malfunctioning, and other sources that introduceunforeseeable or incorrect results.

According to some embodiments, the validation of a treatment table canbe implemented in connection with the table generation system orsoftware. In some cases, the validation of a treatment table can beimplemented in connection with the laser system or software, such asvalidation software residing in the laser system. For instance, aVSS-based validation as described elsewhere herein, which may optionallybe in relation with an aberrometer or wavefront system, can also beimplemented in a laser system. Hence, it is possible to validate atreatment table after it is generated and saved, and it is also possibleto validate a treatment table prior to use in treating a patient. Hence,if a treatment table has been corrupted for some reason, validation andqualification can be performed prior to laser delivery of the ablationpulses, and the treatment can be canceled if disqualification isappropriate.

According to some embodiments, the validation of a treatment table canbe implemented in connection with software residing in a diagnosticdevice such as WaveScan® and iDesign™ devices. System and methodembodiments disclosed herein can also be configured to validatetreatment tables for topographic driven treatment, refraction driven orconventional treatment, and wavefront driven treatment.

Table Generation DLL module 510 can operate to process informationrelated to treatment table generation, Treatment Validation DLL module520 can operate to process information related to treatment validation,Treatment Table module 530 can operate to process information related toa treatment table, and Table Validation module 540 can operate toprocess information related to table validation. In some instances,Table Validation module 540 is configured to embody or implementtechniques described elsewhere herein in relation to Comparison module452. Final Table module 550 can operate to process information relatedto a final table. According to some embodiments, a final tablecorresponding to Final Table module 550 will be the same as a treatmenttable corresponding to Treatment Table module 530, in the event that thetreatment table corresponding to Treatment Table module 530 is validatedor qualified by Table Validation module 540.

Passing Criteria for Treatment Table Qualification

Any of a variety of exam selection criteria can be used to qualify atreatment table generated by the VSS Refractive™ technique. NumerousMonte Carlo simulations have been performed which support thesuitability of such exam selection criteria for treatment tablequalification.

According to some embodiments, the difference in spherical equivalent(SE), cylinder, and cylinder angle can be set or predetermined tosatisfy the following qualification conditions.|dSE|=|dS+0.5dC|=|S ₁ −S ₀+0.5C ₁−0.5C ₀|<0.625  (1)|dC|=|C ₁ −C ₀|≦0.5  (2)|dA|≦1.1538(|C ₀ |+|C ₁|)/2+15.577 (for |C ₀|0.5 and |C ₁|>0.5, orignore)  (3)

As described here, Eq. 1 represents a comparison or difference betweenspherical equivalent, Eq. 2 represents a comparison or differencebetween cylinder, and Eq. 3 represents a comparison or differencebetween axis.

For example, if C₀=0.55 D, C₁=0.5 D, then according to Eq. 1, thecylinder difference is less than 0.5, and thus there may be no need tocheck cylinder angle. For another example, if C₀=0.9 D, C₁=0.8 D, thendA must be smaller than 14.6 degree in order to qualify. Also note thatfor Eq. (2), it is generally desirable that both use the same cylindernotation before the difference can be taken. For example, it isdesirable that both C₀ and C₁ be positive, or that both C₀ and C₁ benegative.

Evaluation and Monte Carlo Simulation

Treatment qualification systems and methods according to embodiments ofthe present invention can be implemented in a variety of ways. There istypically inter-correlation between sphere and cylinder as well as thevertex correction. A scaling factor between a Munnerlyn power and aparabolic power may in some cases depend not only upon the sphererefraction, but also upon on the cylinder refraction. As described inG.-m. Dai, Wavefront Optics for Vision Correction (SPIE Press, 2008),the Munnerlyn shape may differ from a parabolic shape. For example, asdescribed at page 90, supra, the Munnerlyn shape can be 11% deeper thanparabolic shape, when a spherical myopia is considered.

Embodiments of the present invention encompass empirically adjusted andtheoretically based systems and methods for implementing a treatmentqualification technique. Such approaches can include processing a set ofinput refractions (e.g. with sphere between −15 D and +7 D and cylinderbetween −6 D and +6 D) with Munnerlyn shapes, decomposing the data intoZernike polynomials. Zernike decomposition may involve processing pupildimension and tissue volume information to obtain Zernike coefficientand wavefront diameter information, such as data related to a set ofsecond radial order Zernike polynomial terms, and determining therefractions based on the Zernike information. In this way, it ispossible to determine an expected refraction, based on the Zernikecoefficient and pupil dimension information.

Further, these approaches can include regressing the input Munnerlynrefraction against a calculated parabolic refraction using multivariatelinear and quadratic parameters to obtain theoretical scaling factorsfor both sphere and cylinder. Still further, these approaches caninclude using a theoretical algorithm to test in a full implementationwith vertex correction, cosine effect using random keratometry values,and the like, using Monte Carlo simulation with multiple (e.g. 5000)samples. Moreover, these approaches can include refining the theoreticalalgorithm based on the Monte Carlo simulation. What is more, theseapproaches can include retesting the revised algorithm for a new set ofMonte Carlo simulation with multiple (e.g. 5000) samples. According tosome embodiments, such approaches may be implemented in a productionsoftware.

The following formulas give an algorithm for sphere (f_(s)) and cylinder(f_(c)) scaling:f _(s)=1.028−0.00275S−0.00448C (S<0)  (4)f _(s)=1.028−0.00326S−0.00018C (S≧0)  (5)f=1.011−0.005745S−0.00142C  (6)

As indicated here, both S and C can be refractions on the corneal plane.In some cases, it may be desirable to convert the input refractions onvertex plane to the corneal plane before these equations are used.Supposing the refractions on the vertex plane are S₀ and C₀,respectively, it is possible to write:

$\begin{matrix}{S = \frac{S_{0}}{1 - {0.001\; S_{0}d}}} & (7) \\{C = {\frac{S_{0} + C_{0}}{1 - {0.001\left( {S_{0} + C_{0}} \right)d}} - S}} & (8)\end{matrix}$

When f_(s) and f_(c) are calculated, they can be applied to refractionson the corneal plane. For example, suppose the input refractions are −15DS/−5.75 DC×64 @ 12.5 mm vertex. They are used to generate the Munnerlynshape, which has more power than the corresponding parabolic shape. FromEquations (7) and (8), it is possible to obtain the refractions on thecorneal plane as −12.63 DS/−3.84 DC×64 @ 0 mm vertex. Using Equations(4) and (6), it is possible to obtain f_(s)=1.0799 and f_(c)=1.0889.These are scaling factors which may be determined via Monte Carlosimulation. Further, such scaling factors can be applied to an inputrefraction. It can be assumed that the Zernike decomposed refractionsfrom the treatment table are −13.68 DS/−4.09 DC×64 @ 0 mm vertex.

According to some embodiments, for the CustomVue® technique or Wavefrontinput data, there may be no need to use a scaling factor forrefractions, however it may be beneficial to scale the treatment shape11% to achieve a similar target depth corresponding to that ofconventional or VSS Refractive™ input data.

The scaling factors for these refractions can be applied to obtain−12.67 DS/−3.76 DC×64 @ 0 mm vertex, which may correspond to a scaledrefraction on the treatment plane or corneal plane. It is possible toconvert these refractions to a 12.5 mm vertex using Equations (7) and(8), setting d=−12.5 mm. Such conversion corresponds to propagation tothe spectacle plane. Hence, −12.67 DS/−3.76 DC×64 @ 0 mm vertexpropagated to the spectacle plane is −15.05 DS/−5.62 DC×64 @ 12.5 mmvertex. Conversions are useful when comparing refractions, such as anintended refraction and an expected refraction, and this exampleillustrates that it is possible to compare refractions in, for example,a user vertex (e.g. spectacle) plane. Hence, a treatment table power of−13.68/−4.09×64 at 0 mm vertex can be vertex corrected to obtain therefraction as −15.05 DS/−5.62 DC×64 at 12.5 mm vertex. This leaves aresidual error of −0.05 DS/0.13 DC.

The difference in SE can be calculated as (−15.05−5.62/2+15+5.75/2)=0.02D, the difference in Cylinder can be calculated as −5.62+5.75=0.07 D,and the difference in axis can be calculated as 0. If the tolerance forSE is 0.625 D and the tolerance for cylinder is 0.5 D, then these SE andCylinder values are within the tolerances, and hence the treatment canbe approved for release to treat the patient.

FIG. 6 shows a residual error for 5000 simulated cases with 6 mm OZ. Theleft panel shows residual sphere, and the right panel shows residualcylinder, after correction of the scaling factors for 5000 simulatedrealistic cases. If the four outliers are excluded, the spread of sphereis within (−0.4 D, +0.1 D) and that of cylinder is within (−0.2 D, +0.3D), both are in about half a diopter range. Without the exclusion, therange is still within the criteria listed in Eqs. (1) to (3).

Table 1 provides the residual error or residual refractions (indiopters) from a Monte Carlo simulation after implementing the algorithmshown in Eqs. (4) to (6), for optical zones of 7 mm, 6 mm, 5 mm, and 4mm.

TABLE 1 OZ 7 (mm) 6 (mm) 5 (mm) 4 (mm) Rx Sphere Cylinder SphereCylinder Sphere Cylinder Sphere Cylinder N 5000 5000 5000 5000 5000 50005000 5000 Mean −0.043 0.015 −0.043 0.014 −0.045 0.016 −0.013 0.017 Stdev0.054 0.044 0.054 0.044 0.057 0.047 0.045 0.035 Max 0.206 0.480 0.0900.476 0.149 0.432 0.132 0.265 Min −0.564 −0.330 −0.622 −0.215 −0.6100.245 −0.376 −0.171

For the criteria for treatment table qualification, because the residualerrors shown in Table 1 are within the exam selection criteria, it maybe desirable to use the exam selection criteria to qualify treatmenttables in terms of the refraction check. Embodiments of the presentinvention encompass techniques for qualifying an exam, which may involvethe application of treatment table qualification criteria, and selectingthe exam for treatment generation, which may involve the application ofexam selection criteria.

Verification with Production Code and Revised Formulas

Eqs. (4) to (6) were implemented in a production code, and tested withabout 1000 cases with each pupil sizes of 4 mm, 5 mm, 6 mm, and 7 mm.Occasional discrepancies were discovered, and it was determined thatsuch discrepancies may be due to some implementation differences betweenthe C++ code and the Matlab code. Subsequently, a set of new exampleswere generated and regression ran. Results for the new examples weremuch more linear, and the nonlinear behavior previously observed wasabsent.

Table 2 shows the linear factor for different pupil sizes. Scalingfactor data for sphere (f_(s)) and cylinder (f_(c)) was regressed fromdata obtained with the production code for various pupil sizes.

TABLE 2 Pupil Minus Sph Plus Sph Cylinder 4 mm 0.999 1.022 1.010 5 mm1.014 1.037 1.023 6 mm 1.026 1.026 1.014 7 mm 1.023 1.014 1.014 Average1.015 1.025 1.015

Based on the information in Table 2, the original Eqs. (4) to (6) wereadjusted as follows. These equations can override equations (4)-(6).f _(s)=1.015 (S<0)  (9)f _(s)=1.025 (S≧0)  (10)f _(c)=1.015  (11)

As a verification that this new implementation narrows the spread of theresidual error both in sphere and cylinder, the same 5000 samples foreach pupil which were used before, were again used running with theproduction code. This is the revised code based on the adjustmentsdescribed above. FIG. 7 shows the results obtained for a 6 mm pupilusing the revised code, compared with the previous results obtainedusing the original code. Specifically, the upper panels of FIG. 7 showthe residual sphere (left panel) and residual cylinder (right panel) fora 6 mm pupil after correction of the scaling factors for 5000 simulatedrealistic cases using the original Eqs. (4) to (6). In comparison, thelower panels of FIG. 7 show the residual sphere (left panel) andcylinder (right panel) for a 6 mm pupil after correction of the scalingfactors for 5000 simulated realistic cases using the revised Eqs. (9) to(11). From FIG. 7, it can be seen that after the scaling factorrevision, the spread of the residual error in sphere and cylinderbecomes tighter. Therefore, in a normal condition, it is not expectedthat any treatment would fail. However, if a treatment does not satisfya validation test, it can be inferred that something unexpected may havehappened. In such instances, the treatment table can be disqualified,and the treatment will not be applied to the patient. Hence, thisexample illustrates that for validating treatment tables, a set ofnumerical formulas can be developed and validated with multiple MonteCarlo simulations of 5000 cases for each optical zone of 4, 5, 6, and 7mm.

Embodiments of the present invention encompass systems and methods forestimating or determining a scaling factor. Such techniques may involveconstructing a theoretical Munnerlyn shape for all refractive casescovered by the VSS Refractive™ technique (e.g. S and C with increment of0.25 D), calculating a decomposed refraction over a 4 mm diameter, andregressing using a multivariate quadratic regression model. Embodimentsmay also include calculating a wavefront refraction over a pupildimension (e.g. assuming the wavefront diameter is not smaller than thepupil dimension), and converting the refraction to a vertex distance.Embodiments may also include calculating a 2D Munnerlyn shape,decomposing a surface into Zernike coefficients, calculating Zernikepolynomials of each term, calculating Zernike polynomials of arbitrarysize and returning a 2-D surface mesh.

Embodiments of the present invention further encompass systems andmethods based on validation with a Monte Carlo Simulation. Exemplarytechniques may involve performing a validation using Monte Carlosimulation which ensures that implementation of a validation techniquepasses all regular cases within a proposed range, for example a proposed−15 to +7 DS and −6 to +6 DC range for the VSS Refractive™ procedure.Such approaches can be based on a proposed tolerance that is the same asor similar to a an exam qualification, such as 0.625 D for SE and 0.5 Dfor cylinder. For example, for a 6 mm optical zone (OZ) and 12.5 mmvertex, it is possible to input sphere, cylinder, and axis datacorresponding to a vertex plane, and sphere, cylinder, and axis datacorresponding to a corneal plane. Similarly, it is possible to outputsphere, cylinder, and axis data corresponding to a corneal plane.Embodiments also encompass determining scaling factors for sphere,cylinder, and axis, and calculating scaled sphere, cylinder, and axisvalues for corneal and vertex planes. Further, embodiments includedetermining differences between sphere, cylinder, and axis values at acorneal plane. A Monte Carlo simulation can be run with multiple (e.g.1000) random refractions. Embodiments include calculating a predictedrefraction versus a decomposed refraction from the treatment targets.Embodiments may also include calculating a refraction on the cornealplane. In some cases, embodiments encompass determining sphere andcylinder scaling factors. Embodiments may also include determining anempirical scaling factor for Munnerlyn power, where S and C representthe refraction on a corneal surface. Refractions can be converted to thecorneal plane, and scaling factors can be calculated based on cornealrefractions.

The methods and apparatuses of the present invention may be provided inone or more kits for such use. The kits may comprise a system forprofiling an optical surface, such as an optical surface of an eye, andinstructions for use. Optionally, such kits may further include any ofthe other system components described in relation to the presentinvention and any other materials or items relevant to the presentinvention. The instructions for use can set forth any of the methods asdescribed herein.

Each of the calculations or operations described herein may be performedusing a computer or other processor having hardware, software, and/orfirmware. The various method steps may be performed by modules, and themodules may comprise any of a wide variety of digital and/or analog dataprocessing hardware and/or software arranged to perform the method stepsdescribed herein. The modules optionally comprising data processinghardware adapted to perform one or more of these steps by havingappropriate machine programming code associated therewith, the modulesfor two or more steps (or portions of two or more steps) beingintegrated into a single processor board or separated into differentprocessor boards in any of a wide variety of integrated and/ordistributed processing architectures. These methods and systems willoften employ a tangible media embodying machine-readable code withinstructions for performing the method steps described above. Suitabletangible media may comprise a memory (including a volatile memory and/ora non-volatile memory), a storage media (such as a magnetic recording ona floppy disk, a hard disk, a tape, or the like; on an optical memorysuch as a CD, a CD-R/W, a CD-ROM, a DVD, or the like; or any otherdigital or analog storage media), or the like.

All patents, patent publications, patent applications, journal articles,books, technical references, and the like discussed in the instantdisclosure are incorporated herein by reference in their entirety forall purposes.

While the above provides a full and complete disclosure of the preferredembodiments of the present invention, various modifications, alternateconstructions and equivalents may be employed as desired. Therefore, theabove description and illustrations should not be construed as limitingthe invention, which can be defined by the appended claims.

What is claimed is:
 1. A method of evaluating a treatment table for usein an ophthalmologic refractive surgery for a patient, the methodcomprising: inputting a treatment table containing laser ablationinstructions for treating the patient into a treatment instructionsmodule; determining a simulated ablation for the patient based on thelaser ablation instructions with a simulation ablation module;determining an expected optical refraction for the patient based on thesimulated ablation with an expected optical refraction module, whereinthe expected optical refraction for the patient corresponds to highorder aberration information comprising a third order aberration or afourth order aberration; inputting an intended optical refraction forthe patient into an intended refraction module, wherein the intendedoptical refraction for the patient corresponds to high order aberrationinformation comprising a third order aberration or a fourth orderaberration; and evaluating the treatment table by comparing the highorder aberration information corresponding to the expected and intendedoptical refractions for the patient with a comparison module.
 2. Amethod of evaluating a treatment table for use in an ophthalmologicrefractive surgery for a patient, the method comprising: inputting atreatment table containing laser ablation instructions for treating thepatient into a treatment instructions module; determining a simulatedablation for the patient based on the laser ablation instructions with asimulation ablation module; inputting a pupil dimension of the patientinto a pupil dimension module; determining an expected opticalrefraction for the patient based on the pupil dimension and thesimulated ablation with an expected optical refraction module, whereinthe expected optical refraction for the patient is dependent on a sphereophthalmic term characterized by a set of second radial order polynomialterms; inputting an intended optical refraction for the patient into anintended refraction module, wherein the intended optical refraction forthe patient is dependent on a sphere ophthalmic term; and evaluating thetreatment table by comparing the expected and intended opticalrefractions for the patient with a comparison module.
 3. The methodaccording to claim 2, wherein the expected optical refraction and theintended optical refraction each correspond to a common plane.
 4. Themethod according to claim 2, wherein the expected optical refraction andthe intended optical refraction each correspond to a corneal plane. 5.The method according to claim 2, wherein the pupil dimension of thepatient corresponds to a wavefront diameter related to a wavefrontmeasurement of the patient.
 6. The method according to claim 5, whereinthe pupil dimensional of the patient comprises a pupil diameter that isequivalent to the wavefront diameter.
 7. The method according to claim2, wherein the pupil dimension of the patient comprises a pupil diameterof about 4 mm.
 8. The method according to claim 2, further comprisingdetermining if a difference between the expected and intended opticalrefractions for the patient is within a pre-defined tolerance.
 9. Themethod according to claim 8, further comprising qualifying the treatmenttable for use in the ophthalmologic refractive surgery for the patientif the difference between the expected and intended optical refractionsis within the pre-defined tolerance.
 10. The method according to claim8, further comprising disqualifying the treatment table for use in theophthalmologic refractive surgery for the patient if the differencebetween the expected and intended optical refractions is not within thepre-defined tolerance.
 11. A method of evaluating a treatment table foruse in an ophthalmologic refractive surgery for a patient, the methodcomprising: inputting a treatment table containing laser ablationinstructions for treating the patient into a treatment instructionsmodule; determining a simulated ablation for the patient based on thelaser ablation instructions with a simulation ablation module; inputtinga pupil dimension of the patient into a pupil dimension module;determining an expected optical refraction for the patient based on thepupil dimension and the simulated ablation with an expected opticalrefraction module, wherein the expected optical refraction for thepatient is dependent on a spherical equivalent ophthalmic term, acylinder ophthalmic term, and a cylinder angle ophthalmic term;inputting an intended optical refraction for the patient into anintended refraction module, wherein the intended optical refraction forthe patient is dependent on a spherical equivalent ophthalmic term, acylinder ophthalmic term, and a cylinder angle ophthalmic term; andevaluating the treatment table by comparing the expected and intendedoptical refractions for the patient with a comparison module.
 12. Themethod according to claim 11, wherein the evaluating step comprisescomparing the spherical equivalent ophthalmic term corresponding to theexpected optical refraction with the spherical equivalent ophthalmicterm corresponding to the intended optical refraction.
 13. The methodaccording to claim 11, wherein the evaluating step comprises comparingthe cylinder ophthalmic term corresponding to the expected opticalrefraction with the cylinder ophthalmic term corresponding to theintended optical refraction.
 14. The method according to claim 11,wherein the evaluating step comprises comparing the cylinder angleophthalmic term corresponding to the expected optical refraction withthe cylinder angle ophthalmic term corresponding to the intended opticalrefraction.
 15. The method according to claim 11, wherein the evaluatingstep comprises comparing the spherical equivalent ophthalmic termcorresponding to the expected optical refraction with the sphericalequivalent ophthalmic term corresponding to the intended opticalrefraction, comparing the cylinder ophthalmic term corresponding to theexpected optical refraction with the cylinder ophthalmic termcorresponding to the intended optical refraction, and comparing thecylinder angle ophthalmic term corresponding to the expected opticalrefraction with the cylinder angle ophthalmic term corresponding to theintended optical refraction.
 16. The method according to claim 11,wherein the expected optical refraction and the intended opticalrefraction each correspond to a common plane.
 17. The method accordingto claim 11, wherein the expected optical refraction and the intendedoptical refraction each correspond to a corneal plane.
 18. The methodaccording to claim 11, wherein the pupil dimension of the patientcorresponds to a wavefront diameter related to a wavefront measurementof the patient.
 19. The method according to claim 18, wherein the pupildimensional of the patient comprises a pupil diameter that is equivalentto the wavefront diameter.
 20. The method according to claim 11, furthercomprising determining if a difference between the expected and intendedoptical refractions for the patient is within a pre-defined tolerance.